Semifinished product for producing a plastic tube and tube of plastic produced from it

ABSTRACT

A description is given of a semifinished product ( 20 ) for producing plastic tubes comprising a substantially cylindrical body ( 1 ), the one longitudinal end of which goes over into a head part ( 2 ) with a closable squeezing-out opening and the other longitudinal end ( 5 ) of which is formed in an open manner. The semifinished product ( 20 ) is produced in an extrusion blow-moulding process, in which an extruded parison of plastic comprising one or more layers is inflated in a blow mould in conformity with the cavity of the blow mould. The squeezing-out opening provided in the head part ( 2 ) is provided with a one-way closure ( 27 ), which has been created during the inflation process within the blow mould. A plastic tube comprising an elongated body ( 1 ) which is sealed by a pinch/weld portion ( 6 ) is also disclosed.

This application claims priority to PCT Patent Application No. PCT/EP2006/011241 filed on Nov. 23, 2006 and Swiss Patent Application No. 02014/05 filed on Dec. 20, 2005, the entirety of each of which are incorporated by reference.

BACKGROUND

1. Field of the Invention

The invention relates to a semifinished product for producing a plastic tube, which is produced in an extrusion blow-molding process, and a filled plastic tube produced from it according to the preambles of each of the category-defining independent claims.

2. Background of the Invention

Containers made of aluminum sheet, of glass, or of ceramic, which were typical in the past, are increasingly being replaced by containers made of plastic. This is particularly true of tube-like containers that had previously often been made of metal foil. The low weight and low cost surely play a significant role in this substitution. The recyclability of the plastics used is also a significant factor in the increasing acceptance of plastic containers by the end consumer.

Containers for storing and one-time provision of, for example, hair dyes and the like, the contents of which are intended for a single use, must be disposed of after the single use. There is great interest in keeping the volume taken up by the empty container as low as possible. This requirement can be best met particularly by tube-like plastic containers. Precisely for this type of single-use products, there is a desire to keep the production cost and effort as low as possible for the container that must be disposed of after the single use. The tube-shaped containers should be able to be produced using an extrusion blow molding process that is known as such and that ensures great flexibility in production with regard to the plastics used, layer sequencing, and shaping. The tube-shaped containers should be able to be handled as usual, particularly by the bottler, and should be sealable. Reclosable caps or closures should not be necessary. The function of the tube-like container should be self-evident to the end consumer, and the single emptying of the container should be accomplished without effort.

Consideration should also be given to the circumstance that permanent hair coloring dyes are typically sold in combination with a developer, which is usually provided in a separate bottle. Prior to use, the tube contents and the developer must be mixed together. Only when combined with the developer does the hair dye develop the desired effect. Therefore, according to the invention, a tube allows simplified and contaminant-free mixture of the dye contained in the tube and a developer.

This object is achieved by a semifinished product that can be produced in an extrusion blow molding process for producing plastic tubes, and by filled plastic tubes produced from the semifinished product, each having the characteristics listed in the corresponding independent claims. Further developments and/or advantageous embodiments of the invention are the objects of the dependent claims.

SUMMARY OF THE INVENTION

According to the invention, a semifinished product for producing plastic tubes is made as a substantially cylindrical body, one longitudinal end of which transitions into a head part with a closeable squeezing-out opening, and the other longitudinal end of which is formed in an open manner. The semifinished product is produced in an extrusion blow molding process, in which an extruded plastic tube comprising one or more layers is inflated in a blow mold in conformity with the cavity of the blow mold. The squeezing-out opening provided in the head part is provided with a single-use closure that is created within the blow mold during the inflation process.

The semifinished product according to the invention already has a single-use closure and is delivered to the filler in this form. The filler need only fill the planned amount of a pasty mass into the body of the semifinished product through the open longitudinal end, and then seal the open end of the body. This is typically done by pinching together and welding an end section of the open longitudinal end of the body. It can also be, however, that the open end of the body is sealed after filling by sealing or gluing.

For the filler, the advantage of the use of the semifinished product according to the invention is the need only to fill and seal. Complicated and expensive systems for extruding, blowing, filling, and sealing are not needed. The effort for the operation, maintenance, and repair of the required systems is also thus reduced. The production of the semifinished product is done by companies that are specialized and equipped for it. It is simplified and made less expensive, in that a reclosable opening is eliminated and a single-use opening is provided. The head section can thereby be much more simple in design. The single-use closure is generated in the production of the semifinished product, during inflation within the blow mold. The production of the semifinished product is done in a proven extrusion blow molding process, made of an extruded plastic tube comprising one or more layers.

The end user receives a plastic tube with a single-use closure. Specifically for products that are used only once, the probability is thus increased that the entire contents of the tube will actually be used to obtain the desired effect. Mistaken “frugality” that could lead to unsatisfactory and undesired results is prevented, because the end user can no longer close the tube. By eliminating a reclosable closure, the volume of the container to be disposed of after use is also reduced.

A very advantageous embodiment of the invention is to design the single-use closure of the semifinished product as a twist tab closure. Rotating twist tab closures of this type are known and tested, for example, from soft drink bottles. The twist tab closure is an integral part of the head part of the semifinished product. It is of one piece with the head part, and is made of the same material as the body and the head part of the semifinished product, and is produced already during the blow process within the mold cavity of the blow mold. This has the advantage that the end user can dispose of the tube and the twisted-off closure at the same time when disposing of the empty tube, because they are made of the same material.

The twist tab closure has a cap section that is connected to the area of the head part around the squeezing-out opening by a weakened area that is intended as a planned break point. A grip section protrudes from the outside of the cap section. To open it, the body of the plastic tube is held in one hand, and the grip section is gripped with the thumb and index finger of the other hand. By twisting the twist tab relative to the body, the weakened area of the head part designed as a circumferential planned break point breaks open, and the cap section can be removed. The squeezing-out opening is now exposed, and the tube contents can be dispensed from the squeezing-out opening.

The twist tab closure is advantageously produced already when the semifinished product according to the invention is extrusion blow molded. The circumferential planned break point is formed in the cavity of the blow mold. The grip section is formed from a pinched section of the extruded plastic tube. The production of the twist tab closure during the extrusion blow molding process does not require any additional process step or additional time.

An advantageous embodiment of the semifinished product according to the invention is that the head part has an outer contour that deviates from the circular, and has at least one venting surface. For permanent hair dye products, the dye in the tube and the developer in a bottle are sold as a set. The dye contained in the tube must be mixed with developer before the mixture can be applied. The neck width of the bottle and the tube are thereby advantageously matched to one another, so that the head part of the tube can be introduced into the bottleneck. With the design according to the invention, the at least one venting surface allows the air in the bottle to escape that is compressed when the tube contents are squeezed out into the developer in the bottle. This can prevent contamination of the working surface.

The semifinished product is advantageously formed from a multiple layer extruded plastic tube that has a barrier layer to keep out light, oxygen, and moisture. Particularly in the embodiment of the semifinished product with a twist tab, the multiple layer construction is ensured even in the area of the closure cap, and a 100 percent barrier can be achieved. In a further, very convenient embodiment of the invention, the semifinished product formed from a multiple layer plastic tube has a getter layer for oxygen. The multiple layer semifinished product can have 3 to 6 or more layers. According to the invention, at least one of the layers can be made from regenerated plastic waste and residue, known as reclaimed grind.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional advantages and characteristics are found in the below description of an embodiment of the application example of the invention, with reference to the schematic drawing, Shown, not to scale, are:

FIG. 1 is a perspective view of an application example of the semifinished product according to the invention, with integrally designed single-use closure;

FIG. 2 is a side view of the semifinished product of FIG. 1;

FIG. 3 is a section view of the head part of the semifinished part as in FIGS. 1 and 2;

FIG. 4 is a cross section through the transition of the single-use closure into the head part of the semifinished product;

FIG. 5 is a cross section through the head part of the semi-finished product;

FIG. 6 is a side view of a filled plastic tube produced from the semifinished product as in FIG. 1-5; and

FIG. 7 is a perspective view of the plastic tube as in FIG. 6.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1-5 show an application example of the semifinished product according to the invention in various views and sections. The semifinished product as a whole is identified as 20. The semifinished product 20 produced in an extrusion blow molding process for the production of a plastic tube has an elongated, substantially cylindrical body 1, on one longitudinal end of which a head part 2 abuts. The opposite longitudinal end 5 of the body 1 is formed in an open manner. To produce the semifinished product 20, an endless plastic tube comprising one or more layers is extruded using an extrusion orifice, then cut, and inflated with positive pressure in a blow mold in conformity with the cavity of the blow mold. The extrusion and inflation process is done using extrusion blow molding machines that are sufficiently known from the state of the art, and that allow the simultaneous production of a plurality of semifinished products.

The head part 2 has a squeezing-out opening 3 that is surrounded by an edge section. The squeezing-out opening is closed by a single-use closure made of one piece with the head part 2, said closure being particularly designed as a twist tab closure 27. The twist tab closure 27 has a cap section 30 that is connected to the area of the head part 2 around the squeezing-out opening 3 by a weakened area 29 that is intended as a planned break point. A grip section 28 protrudes from the outside of the cap section 30, said grip section having a flattened form and, for example, a rippled contour. The grip section 28 makes it easier to grip the twist tab closure 27, which is twisted relative to the head part 2 to break open the planned break point 29. The production of the twist tab closure 27 takes place during the inflation of the extruded plastic tube within the mold cavity of the blow mold. The grip section 28 is produced, for example, simply by pinching a section of the tube.

FIG. 4 shows an embodiment of the weakened area 29 designed as a planned break point at the transition from the cap section 30 to the head part 2. Constrictions are planned, for example, that lead to a cross-sectional contour of the weakened area 29 that deviates from the circular cross sectional shape.

FIG. 5 shows a cross section of the head part 2. This has an outer contour that deviates from the circular form, and is achieved, for example, by a sequence of sealing surfaces 24 and venting surfaces 25. The sealing surface 24 has approximately the radius of curvature of a complete circular outside contour. The venting surfaces 25, in contrast, are concavely indented. For permanent hair dyes, the dye in the tube and a developer in a bottle are sold as a set. The dye contained in the tube must be mixed with the developer before the mixture can be used. The neck width of the bottle and the tube are thereby advantageously matched to one another, so that the head part of the tube can be introduced into the bottleneck. With the design according to the invention, the sealing surfaces 24 on the head part 2 provide support and a certain sealing location in the bottleneck. The concave venting surfaces 25 allow the air in the bottle to escape that is compressed when the tube contents are squeezed out into the developer in the bottle. This can prevent contamination of the working surface.

The semifinished product 20 produced by an extrusion blow molding process, with the integrated twist tab closure 27, is filled by the filler with a pasty mass or the like, such as a hair dye product, through the open longitudinal end. The longitudinal end 5 is then closed off. This is done, for example, by pinching together and welding, or by sealing or gluing, and is shown in FIG. 6 and FIG. 7 as a pinched/welded section 6. This results in the characteristic shape of a filled plastic tube 21. FIG. 6 and FIG. 7 show the plastic tube 21 with an intact twist tab closure 27. By twisting the twist tab closure 27 relative to the head part of the body 1, the planned break points are broken open and the squeezing-out opening is exposed. The contents of the plastic tube 21 can be simply squeezed out, aside from a small remnant. The twist tab closure 27 is made of the same material as the body 1 of the plastic tube 21 and can be disposed of with it after the contents are squeezed out. 

1. A semifinished product for producing plastic tubes, comprising: a substantially cylindrical body, one longitudinal end of which transitions into a head part a with a closeable squeezing-out opening, and another longitudinal end of which is formed in an open manner; the substantially cylindrical body formed from an extruded plastic tube comprising one or more layers inflated in a blow mold in conformity with a cavity of the blow mold; the squeezing-out opening having a single-use closure that is generated during the inflation process within the blow mold.
 2. The semifinished product of claim 1, wherein the single-use closure (27) is a twist tab closure.
 3. The semifinished product a of claim 1, wherein the twist tab closure is an integral part of the head part, is designed to be of one piece with the head part, and is made of the same material as the body and the head part.
 4. The semifinished product of claim 3, wherein the twist tab closure has a cap section that is connected to a section of the head part bordering the squeezing-out opening by a weakened area that is designed as a planned break point, and further comprising a grip section extending from the cap section.
 5. The semifinished product of claim 4, wherein the planned break point is produced in the cavity of the blow mold, and the grip section is formed from a flattened section of the extruded plastic tube.
 6. The semifinished product of claim 1, wherein the head part has an outer contour that deviates from a circular shape, and that is provided with at least one venting surface.
 7. The semifinished product of claim 1, wherein the extruded plastic tube has multiple layers, and has a barrier layer that provides a barrier against light, oxygen, and moisture.
 8. The semifinished product of claim 1, wherein the extruded plastic tube has multiple layers, and has a getter layer for oxygen.
 9. A plastic tube, comprising a longitudinal body for containing a pasty mass, the longitudinal end of which has a head part with a squeezing-out opening and the opposite longitudinal end closed off using a pinch/weld section; the substantially cylindrical body formed from an extruded plastic tube comprising one or more layers inflated in a blow mold in conformity with a cavity of the blow mold; the squeezing-out opening having a single-use closure that is generated during the inflation process within the blow mold; and whereby the pinch/welding section is generated after filling the longitudinal body with a pasty mass.
 10. The plastic tube of claim 9, wherein the single-use closure comprises a twist tab closure.
 11. The plastic tube of claim 10, wherein the twist tab closure is an integral part of the head part, is designed to be of one piece with the head part, and is made of the same material as the body and the head part.
 12. The plastic tube of claim 11, wherein the twist tab closure has a cap section that is connected to a section of the head part bordering the squeezing-out opening by a weakened area that is designed as a planned break point, and further comprising a grip section extending from the cap section.
 13. The plastic tube of claim 12, wherein the planned break point is produced in the cavity of the blow mold, and the grip section is formed from a flattened section of the extruded plastic tube.
 14. The plastic tube of claim 9, wherein the head part has an outer contour that deviates from a circular shape and is provided with at least one venting surface.
 15. The plastic tube of claim 9, wherein the extruded plastic tube has multiple layers and has a barrier layer that provides a barrier against light, oxygen, and moisture.
 16. The plastic tube of claim 9, wherein the extruded plastic tube has multiple layers and has a getter layer for oxygen. 